Device for operating dental hand pieces

ABSTRACT

A device which can be used for operating a dental hand piece with a motor drive and a dental hand piece with a pneumatic drive, such as a turbine drive, has an electric circuit and a potentiometer connected to the input of the circuit and varying the voltage at its output. An electric valve varies the flow volume of the compressed air supplied to the pneumatic drive. A switching device connects selectively the electric motor and the electric valve with the output of the circuit.

0 United States Patent Fleer et al. Se t. 2 1975 [54] DEVICE FOROPERATING DENTAL HAND 3,209,457 10/1965 Billin et a1. 32/22 PIECES3,250,006 5/1966 Wilson, Jr 32/28 3,702,940 11/1972 Stewart 32/22 [75]Inventors: Otto Fleer, Erlangen; Hubert Grill,

Pfungstadt both of Germany Primary Examiner-Robert Peshock [73]Assignee: Siemens Aktiengesellschaft, Munich, Assistant Examiner.l. Q.Lever Germany Attorney, Agent, or Firm-Richards & Geier [22] Filed: May3, 1973 21 Appl. No.: 356,752 [57] ABSTRACT A device which can be usedfor operating a dental Apphcatlon Data hand piece with a motor drive anda dental hand piece [63] g f of May with a pneumatic drive, such as aturbine drive, has an 1970 electric circuit and a potentiometerconnected to the input of the circuit and varying the voltage at itsout- [22] i185] 31/6212, put. An filectric valve varies the flow volumeof the 'f i 28 4 compressed air supplied to the pneumatic drive. A oearc switching device connects selectively the electric motor and theelectric valve with the output of the cir- [56] References Cited cuitUNITED STATES PATENTS Staunt 32/22 4 Claims, 2 Drawing Figures PATENTEDSEP 2 I975 SHEET 1 OF 2 DEVICE FOR OPERATING DENTAL HAND PIECES Thepresent application is a continuation-in-part of our copending patentapplication Ser. No. 48,616, filed May 15, 1970, now U.S. Pat. No.3,844,039.

This invention relates to a device for operating dental hand pieces.

Dental hand pieces with movable instruments are used for the treatmentof teeth. It is required to use for such a treatment instruments withmany different speeds. Such requirements cannot be taken care of by asingle one hand piece. Consequently dental units have been providedwhich have electrical drives as well as compressed air turbine drives.The dentist decides depending upon the required treatment whether tooperate with the turbine with a very high number of revolutions or withthe electric motor drive with a low number of revolutions.

In case of hand pieces with a drive by an electric motor it is known tovary the number of revolutions of the drive within predetermined limitsby a circuit device. This operational possibility does not existfor handpieces with a compressed air drive, since most foot operated devices forsupplying pressure means to the compressed air drive are in knowndevices only black and white switching devices, so that in these devicesa magnetic valve located in the compressed air conduit can be eithercompletely opened or completely closed.

An object of the present invention is the provision of a device foroperating dental hand pieces which will greatly simplify theconstruction and service of the handpieces. The device of the presentinvention should have the largest amount of similar parts and should beable to control the r.p.m. of hand pieces with an electric motor driveas well as those with compressed air drive within wide limits.

Other objects of the present invention will become apparent in thecourse of the following specification In the accomplishment of theobjectives of the present invention it was found desirable to provide adevice for operating a dental hand piece with a motor drive and a dentalhand piece with a pneumatic drive, such as a turbine drive, comprising acurrent source, an electric circuit connected to the current source, apotentiometer connected to the input of the circuit and varying thevoltage at its output, an electric valve varying the flow volume ofcompressed air supplied to the pneumatic drive and switching meansconnected to said output and connecting selectively the electric motorand the electric valve with the output of the circuit.

The advantages of this deviceof the present invention include a savingin structural elements since it is not necessary to provide each drivewith its own supply. On the contrary, all drives are actuated by asingle common controlling device. The switching means can be so arrangedthat they are actuated when an instrument with a hand piece is removedfrom the storing carrier. In case of a hand piece with compressed airdrive the electrical adjusting member consists of an electrical valveoperating compressed air supplied to the drive. The valve operating thenumber of revolutions of an air pressure drive can preferably contain apiston operating the cross-section of the passage of the valve, thepiston being adjustable by the magnetic rotor of the raising magnet. Thepiston can be guided so that it will move axially and can be providedwith an axially extending radial part which interconnects the inlet andoutlet openings of the valve and changes depending on the position ofthe piston the free passage cross-section of the valve.

The invention will appear more clearly from the following detaileddescription when taken in connection with the accompanying drawingsshowing by way of example only, preferred embodimens of the inventiveidea.

IN THE DRAWINGS FIG. 1 is a circuit diagram illustrating a device of thepresent invention for controlling a dental hand piece driven by anelectric motor and a hand piece driven by compressed air.

FIG. 2 is a section through the regulating valve of FIG. 1.

The device shown in FIG. 1 is used for controlling the number ofrevolutions of an instrument hand piece 1 driven by an electric motorand the number of revolutions of an instrumenthand piece 2 driven byair. The hand pieces I and 2 are placed in supports 3 and 4 in or upon aconveniently located storer not shown in the drawings. The supports 3and 4 are so mounted that when a hand piece is removed the switch 5 orthe switch 6 will be actuated. This is produced by the pulling force oftwo traction springs at the supports and the diminution of weight when ahand piece with the instrument is removed.

The switch 5 switches on the circuit for the electric motor 7 located inthe hand piece 1 and the switch 6 switches on the circuit for the supplyof compressed air to a turbine actuated by an electromagnetic valve 8and located in the head of the hand piece 2. Compressed air is producedby an air compressing device 9 and is supplied to the hand piece 2 by acompressed air conduit 10. The conduit 10 also carries a pressurereducing valve 11. The valve 8 is connected with the switching contactsof the changeover switch 6. The electric motor 7 located in the handpiece I is connected with the switching contacts of the switch 5. Thetwo switches 5 and 6 are so constructed and so interconnected that onlythe hand piece removed from its support can be operated. The circuit ofthe other hand piece is interrupted. This locking arrangement is mostadvantageous since the user of the instruments provided with the handpieces does not have to decide which of the drives should be operated.The two feed lines 12 and 13 to the motor 7 and to the winding of theelectrical valve 8 are connected with the outputs 14 and 15 of a circuitdevice 16. The circuit device 16 provides the means for controlling thenumber of revolutions of a dental borer driven by an electic motor, forexample the switch arrangement for the driving motor 7. At the input ofthe circuit device 16 which is fed from a source 17 of alternatingcurrent are connecting lines axtending to a regulatable resistance orpotentiometer 18. The potentiometer 18 can be built into an actuatingdevice operated by foot or it can be constructed as a shiftingpotentiometer actuated by hand. Its switch 19 switches on and off therespective drive (for the motor 7) or the electrical adjusting device ofthe drive (the magnetic valve 8). The switch 19 is ad- I vantageouslycoupled with the variable part of the potentiometer 18.

The circuit device 16 must carry out several functions for electricalborer drives, namely it must provide a continuous adjustability for ther.p.m., it must keep the r.p.m. constant independent of the load, itmust limit the current flow and it must provide a reversal of thedirection of rotation of the drive.

The present specification will describe only the switch circuit requiredfor the continuous adjustment of the number of revolutions since onlythis part of the circuit device is of importance for the subject matterof the present invention.

For the adjustment of the number of revolutions are necessary thepotentiometer 18 as variable resistance, the resistance 20 for limitingthe upper number of revolutions, the resistance 21 for providing a limitfor the lower number of revolutions, the transistors 22, 23, 24 and 25,as well as resistances 26 to 32, diodes 33 and 34 as well as directvoltage supply 35. At the transistor 24 which is located in the motorrotor circuit as a variable resistance, there is the certain voltage UThe base of the transistor'23 is actuated by the collector potential ofthe transistor 22. At the base-emitter stretch of this transistor 22lies the actuating voltage U U (U- ,+lXR The pre-voltage U is taken froma voltage divider formed by resistances l8 and 20, its voltage beingheld constant by the zener diode 33 independent of the amount of directvoltage applied from the voltage source 35. The smaller becomes thevoltage U by the potentiometer 18 which sets the r.p.m., the smallerwill be the base-emitter voltage U at the transistor 22 which then locksmore. Then its collector potential will become more positive. The resultis that the transistors 23 and 24 will open more. This reduces thevoltage at the collector-emitter stretch of the transistor 24, and thisresults in that the voltage at the motor 7 will correspondingly increaseand thus its revolutions will increase. A load dependent resistance isindicated by the numeral 31 in FIG. 1. The revolutions of the motor 7decrease with a greater set voltage U in a manner similar to the onedescribed.

Thus with this circuit device a variable voltage can be produceddepending upon the setting of the potentiometer 18 at the outputs 14 and15 of the controlling device 16 and this voltage can be used to changeselectively within predetermined limits the rpm. of the motor 7 or theregulating valve 8 as far as its flow passage is concerned. If the handpiece 1 is removed from its support 3, the outgoing voltage of thecircuit device 16 is transmitted through the change-over switch 5 to themotor drive. At the same time the switches 5 and 6 make certain that thecircuit of the hand piece 2 which is not used, remains interrupted andthat the valve 8 cannot be switched on, so that these parts are locked.

As shown in FIG. 2, the valve 8 consists substantially of two mainparts, namely, a stroke magnet 40 and a throttle valve 41. Inside themagnet 40 there is located a magnetic armature or plunger 42 which ismoved axially in the direction of the arrow when the magnetic winding 43is excited. A piston 44 located in the valve 41 and also movable axiallyis actuated by the magnetic armature 42. The piston 44 has a radialrecess 45 extending in its axial direction for connecting air inlet 46through the two openings 48 and 47 to the outlet 49. Thus compressed aircan flow to the turbine located in the hand piece 2 and drive it. Thegreater the excitation of the magnet 40 the greater will be the freecrosssection provided by the piston 44 between the openings 47 and 48. Aspring 50 presses the piston 44 against the action of the magnet and isso dimensioned that a linear movement of the piston 44 is possible. Thevalve operates in a voltage range of 8 to 20 v. The voltage 20 v.corresponds then to the final number of rotations of the driving motor8.

The advantage of this construction is that for a hand piece with anelectric drive and a hand piece with a turbine drive only a singleproviding circuit and a single operating device are necessary. Anotheradvantage of the construction is that it is necessary to have only asingle switch and only one regulating device for said two hand pieces.

What is claimed is:

1. A device for operating a dental hand piece with a motor drive and adental hand piece with a pneumatic drive, such as a turbine drive, saiddevice comprising a current source, an electric circuit device connectedto the current source and having an input and an output, a potentiometerconnected with said input and varying the voltage at the output, anelectric valve varying the flow volume of the compressed air suppliedvto the pneumatic drive, and switching means connected with said outputand connecting selectively said electric motor and said electric valvewith the output of that circuit device, wherein said electric circuitdevice including an operating resistance connected with saidpotentiometer and a transistor having a collector-emitter connectionconnected in parallel with said operating resistance, saidpotentiometerbei ng connected in parallel to said collector-emitterconnection and said motor drive and in series to said operatingresistance and influencing the bas'ic,potential of said transistor.

2. A device for operating a dental hand piece with a motor drive and adental hand piece with a pneumatic drive, such as a turbine drive, saiddevice comprising a current source, an electric circuit device connectedto the current source and having an input and an output, a potentiometerconnected with said input and varying the voltage at the output,anelectric valve varying the flow volume of the compressed air suppliedto the pneumatic drive, said valve comprising a casing having a flowpassage, a valve body and a magnetic armature for moving said valve bodydepending upon the voltage of the outlet of the electric circuit devicefor varying said flow passage, and switching means connected with saidoutput and connecting selectively said electric motor and the magneticarmature of said electric valve with the output of the circuit device.

.3. A device for operating a dental hand piece with a motor drive and adental hand piece with a pneumatic drive, such as a turbine drive, saiddevice comprising a current source, an electric circuit device connectedto the current source and having an input and an output,

a potentiometer connected with said input and varying the voltage at theoutput, an electric valve varying the flow volume of the compressed airsupplied to the pneumatic drive, and switching means connected with saidoutput and connecting selectively said electric motor and said electricvalve with the output of the circuit device. wherein said electricalvalve comprises a casing having a flow passage, a piston movable in saidcasing to adjust said passage, astroke magnet and a magnetic armaturecarried by said stroke magnet and actuating said piston.

4. A device in accordance with claim 3, wherein said piston is axiallymovable in said casing and comprises an axially extending radial recessadapted to interconnect opposite ends of said passage and varying theextent of flow in said passage,

1. A device for operating a dental hand piece with a motor drive and adental hand piece with a pneumatic drive, such as a turbine drive, saiddevice comprising a current source, an electric circuit device connectedto the current source and having an input and an output, a potentiometerconnected with said input and varying the voltage at the output, anelectric valve varying the flow volume of the compressed air supplied tothe pneumatic drive, and switching means connected with said output andconnecting selectively said electric motor and said electric valve withthe output of that circuit device, wherein said electric circuit deviceincluding an operating resistance connected with said potentiometer anda transistor having a collector-emitter connection connected in parallelwith said operating resistance, said potentiometer being connected inparallel to said collector-emitter connection and said motor drive andin series to said operating resistance and influencing the basicpotential of said transistor.
 2. A device for operating a dental handpiece with a motor drive and a dental hand piece with a pneumatic drive,such as a turbine drive, said device comprising a current source, anelectric circuit device connected to the current source and having aninput and an output, a potentiometer connected with said input andvarying the voltage at the output, an electric valve varying the flowvolume of the compressed air supplied to the pneumatic drive, said valvecomprising a casing having a flow passage, a valve body and a magneticarmature for moving said valve body depending upon the voltage of theoutlet of the electric circuit device for varying said flow passage, andswitching means connected with said output and connecting selectivelysaid electric motor and the magnetic armature of said electric valvewith the output of the circuit device.
 3. A device for operating adental hand piece with a motor drive and a dental hand piece with apneumatic drive, such as a turbine drive, said device comprising acurrent source, an electric circuit device connected to the currentsource and having an input and an output, a potentiometer connected withsaid input and varying the voltage at the output, an electric valvevarying the flow volume of the compressed air supplied to the pneumaticdrive, and switching means connected with said output and connectingselectively said electric motor and said electric valve with the outputof the circuit device, wherein said electrical valve comprises a casinghaving a flow passage, a piston movable in said casing to adjust saidpassage, a stroke magnet and a magnetic armature carried by said strokemagnet and actuating said piston.
 4. A device in accordance with claim3, wherein said piston is axially movable in said casing and comprisesan axially extending radial recess adapted to interconnect opposite endsof said passage and varying the extent of flow in said passage.